Acetabular Revision Surgery with Tantalum Trabecular Metal Acetabular Cup for Failed Acetabular Cage Reconstruction with Bone Allografts: A Retrospective Study with Mid- to Long-Term Follow-Up

Abstract

Background: Acetabular cage reconstruction with bone allografts is among the successful strategies to deal with massive acetabular bone loss. However, the nonbiological fixation nature of cages can compromise long-term success. Tantalum trabecular metal acetabular cups (TM cups) have been used in acetabular revision surgery because of their increased initial stability and good bone ingrowth features. This study was performed to determine whether the bone stock of the acetabulum is enough to support a hemispheric TM cup after failed cage reconstruction with bone allografts. Methods: We retrospectively reviewed patients who received acetabular revision surgery with TM cups after failed cage reconstruction with bone allografts from 2006 to 2017. There were 12 patients (5 males and 7 females) included in this study, with a mean age of 61.5 years (38 to 81) at the time of re-revision surgery. The mean follow-up after re-revision surgery was 8.6 years (2.6 to 13.3). The endpoint was defined as the aseptic loosening of the TM cup and reoperation for any causes. The change in bone stock of the acetabulum between index revision and re-revision was assessed according to the Gross classification for acetabular bone loss. Results: One patient died after eight years of follow-up of a cause not related to hip surgery. Two patients received two-stage revision arthroplasty due to PJI after 3.2 and 9.4 years of follow-up, respectively. The bone stock of the acetabulum was significantly improved between index revision and re-revision surgery (p < 0.0001). The Kaplan−Meier survivorship was 100% with aseptic loosening as the endpoint and 90% and 75% at five- and ten-year follow-up, respectively, with reoperation for any reason as the endpoint. Even cage reconstruction with bone allografts will fail eventually, and the bone stock of the acetabulum will improve after union and incorporation between host bone and allografts. The restored bone stocks will facilitate further revision surgery with hemispheric TM cups. The biological fixation between host bone and tantalum trabecular metal can provide longstanding stability of the TM cup. Conclusions: The results of our study offer a viable option for patients with failed cage reconstruction with bone allografts.

Keywords: failed cage reconstruction; revision hip arthroplasty; tantalum trabecular metal acetabular cup.

Figure 1

(A) The host bone of acetabulum was bleeding after reaming in re-revision surgery, indicating revascularization of allografts. (B) The allografts, which were implanted in index revision, had non-vascularized areas (marked with *) during re-revision surgery.

Figure 2

Acetabulum bone loss significantly decreased between index revision and re-revision according to Gross classification (p < 0.001).

Figure 3

(A) Paprosky type IIIA acetabular bone defect after operation for periprosthetic joint infection. (B) Reconstruction of acetabulum bone loss with cage and bone allografts. (C) Cage failure eight years after index revision. Radiolucent line between cage and host bone (arrow), with union of the host bone and allografts (*) were shown. (D) The TM cup remained stable after nine years of follow-up after re-revision surgery.

Figure 4

The Kaplan–Meier survivorship was 100% with aseptic loosening as the endpoint, and 90% and 75% at five- and ten years, respectively, with reoperation for any reason as the endpoint.